Antenna rewrites GSM micro basestation economics

Antenova has developed an innovative antenna design it reckons changes the economics of the micro basestations used to optimise cell coverage.

Antenova has developed an innovative antenna design it reckons changes the economics of the micro basestations used to optimise cell coverage.

Called HDA 1000, the new antenna uses 'in-air' mixing to eliminate the conventional duplexer or multicasting hardware that combines the broadcast RF carrier signals from two or more transceivers.

In addition to saving several hundred dollars of hardware costs, this eliminates some 3.6dB of transmission power losses - giving basestation operators typically 20% further range and a potential increase in micro cell footprint of over 40%.

As has been proven in beta trials with a major European mobile operator, the increase in cell coverage made possible by the HDA 1000 delivers significant benefits - supporting higher site traffic levels and reducing dropped calls.

In order to combine carrier signals from multiple transceivers in the air, conventional antennas must be physically separated by a substantial distance to avoid crosscoupling.

For GSM frequencies, this spacing needs to be of the order of a metre.

Such an antenna separation is possible on a macro basestation, but is not typically used on micro basestations due to the aesthetic considerations and physical constraints imposed by urban and office installation locations.

It is possible to get the required isolation with a much closer spacing between the antennas using Antenova's unique high dielectric antenna (HDA) technology.

The use of high-dielectric ceramic materials in Antenova's HDAs results in a highly localised near field around the antenna.

This feature allows antennas to be mounted within millimetres if required, without suffering coupling effects - facilitating 'in-air' mixing.

The antenna elements also provide highly uniform radiation patterns for overlapping coverage.

This ensures that the broadcast control channel (BCCH) - which is usually only transmitted by one of the transceivers - is 'visible' to all handsets in the cell.

"The performance and size of micro basestations is very important for operators, who need to enhance network infrastructure to deliver on their business objectives, while also meeting aesthetic and physical considerations", says Greg McCray, CEO of Antenova.

"Antennas are a crucial part of the solution, and this advance in antenna technology is an enabling force for better basestation design".

Antenova's HDA 1000 design provides dual omnidirectional antennas comounted inside a 250 x 40 x 27mm case.

This compact form factor helps designers to achieve the very small system sizes increasingly required for micro basestations, in order to fit into available spaces such as inside lampposts or retail shop signage - and avoid 'visual blight'.

HDA 1000 is designed for the GSM 1800 band and operates over the 1710 to 1880MHz frequencies.

A wideband version of the antenna is currently under development and other frequency bands can be provided upon request.

Despite the small physical separation of the two antenna elements, the product provides over 20dB of isolation between ports and a peak gain of 2.5dBi.

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